Let p be a prime integer and n≥3 be a natural number such that pn−1 has a primitive prime divisor. Also let n=λ1+⋯+λm such that n>λi≥1 for all i. I want to show that (pλ1−1)⋯(pλm−1) does not divide pn−1.
This is my suggested argument for proving the statement when p>2:
Both of (pλ1−1)⋯(pλm−1) and pn−1 are polynomials in p with the same degree. If (pλ1−1)⋯(pλm−1)∣pn−1, we then have pn−1=c(pλ1−1)⋯(pλm−1), where c∈N. Since p>2, pλi−1>1 for all i. Therefore, the coefficient of pλ1+...+λm=pn in the expansion of the product ∏mi=1(pλi−1) is 1. Also the coefficient of pn in pn−1 is 1, and so we must have c=1 . Therefore pn−1=(pλ1−1)⋯(pλm−1). Now if we consider q to be primitive prime divisor of pn−1, then q does not divide (pλ1−1)⋯(pλm−1), which is a contradiction. So if p>2, it is impossible for (pλ1−1)⋯(pλm−1) to divide pn−1.
But as it was discussed in comments, it seems that my argument is not true.
Question 1: Does my argument work? If not, is there any possible way to prove the statement for p>2?
The remaining case is when p=2. According to the example mentioned in comments (2−1)(22−1)(23−1)∣26−1.
Question 2: Is there any example of a pair (n,p)≠(6,2) and a partition $\lambda=(1\leq\lambda_1\leq...\leq\lambda_m
No comments:
Post a Comment